Re: AGP or PCI

On 9 May 2006 22:41:05 -0700, "paulmd@xxxxxxx" <paulmd@xxxxxxx> wrote:
Carlos CZ wrote:

Finally I finded the root of my contradictions,
what happened is that my book only show two posibilities:

* or you use a PCI bus controller,
* or an AGP bus controller that replaces completelly the
PCI controller, yes, there is no PCI here.

That's completely inaccurate.

AGP is not a bus, in the sense that it supports multiple devices; it
is for one display controller only. It was developed soon after the
Pentium II was released as a way to relieve the display controller of
the bottleneck posed by PCI's 33MHz-by-32-bits standard.

AGP did the following to do that:
- increased clock speed to 66MHz
- transfer 2 bits per every clock cycle for 133MHz
- allowed fast access to system RAM for 3D textures etc.

Later revisions of AGP increased the number of bits per clock pulse
(while the clock stayed at 66MHz) and dropped the operating voltage to
facilitate this. That's why you can't mix old AGP motherboards with
new AGP cards and vice versa, if the voltages don't match!

An AGP-era motherboard always has PCI as well as the single AGP.
There may be onboard graphics that are internally AGP, an AGP slot, or
both - but when both are present, only one works at a time.

AGP has now been superceded by PCI Express, which offers a more
flexible way of combining units of bus throughput to taste. So far,
PCI Express motherboards come with legacy PCI slots, new PCI Express
slots using 1 bandwidth unit each, and a single 16-unit PCI Express
slot for the display controller where the AGP slot used to be.

You don't get AGP and PCI Express on the same motherboard.



--------------- ----- ---- --- -- - - -
Tech Support: The guys who follow the
'Parade of New Products' with a shovel.
--------------- ----- ---- --- -- - - -
.

Relevant Pages

  • Re: Asus p5v800 vs Asrock 775 dual 880
    ... HD and these boards support both AGP and PCI Express (for when I ... I understand the Asrock supports dual channel memory, ... In other words, the Asrock board has two video card slots, ...
    (alt.comp.periphs.mainboard.asus)
  • Re: AGP or PCI
    ... If you are looking at the choice offered in BIOS for PCI or AGP graphics, ... If my machine uses the PCI bus controller or the AGP bus controller, ...
    (microsoft.public.windowsxp.hardware)
  • Re: AGP or PCI
    ... the CPU splits into the PCI bus and AGP bus via PCI and AGP controller ...
    (microsoft.public.windowsxp.hardware)
  • Re: AGP or PCI
    ... the CPU splits into the PCI bus and AGP bus via PCI and AGP controller ...
    (microsoft.public.windowsxp.hardware)
  • Re: AGP or PCI
    ... The PCI bus CAN NOT BE REPLACED BY THE AGP BUS.. ... but the fact that the PCI controller could to be ...
    (microsoft.public.windowsxp.hardware)